Hello NC500,
A note on coil springs. Hotchkis sells only one front coil spring for the 3rd gen. If you look in the Ford Master Parts catalogue, there are dozens of different front springs offered alone for the '66 full size. Ford carefully designed and selected springs for the body type (2dr, 4dr, hardtop, post, etc), then engine type, transmission type, manual or power steering and air conditioning. Then they even have heavy duty springs listed as well. The weight difference on a '66 full size vastly varies for the above possibilities. There is no way Hotchkis can realistically say it will work in your car at this ride height.
Since these galaxie components were designed for Jay Leno's '66 gal 500 7 litre, it's going to match his weight with all his options, not anyone else's unless it just happens to match. Another thing too, if you want to lower your car without properly designed drop spindles you may want to check your bump steer, caster and camber arc. This is because the caster, camber and bump steel are at optimal levels at designed ride height. Usually the further up or down from nominal ride height the caster, camber and bump steer can start drastically changing and result in a poor driveability.
Cheers